A Time-harmonic Inverse Design of Uniplanar RF Coil for Unilateral NMR Sensors

A time-harmonic inverse method was employed to design a uniplanar radio-frequency (RF) coil for unilateral nuclear magnetic resonance (UNMR) sensors to improve coil sensitivity and signal-to-noise ratio. In the design, an ideal current density was calculated on a planar surface and generated a specified magnetic field, which was perpendicular and correlated with a given in-homogenous main magnetic field with a constant linear static gradient in the region of interest. The basic functions of the current density were represented by a Fourier series, and a simple matrix inversion approach was utilized to obtain the corresponding current coefficients. Stream function techniques were then used to implement this theoretical current density into an RF coil. A uniplanar RF coil for a UNMR sensor was designed and constructed, and the results were presented.